The strongly brain-based theory underlying the approach to earliest intervention described here has been tested in several experimental studies, which are designed to investigate the effects of planned purposeful modification of experience for very early born infants, who spend the third trimester of gestation in the NICU. NIDCAP is based on an approach which utilizes close observation of each infant's thresholds of moving from organization to disorganization and stress, as exhibited by the infant's behavior. Care and environment are then continuously dynamically adjusted, with the goal to increase the infant's self-regulation and organization and decrease the infant's stress. This individualized model of NICU care provides an opportunity to investigate the modifiability of very early born infants' brain function and structure and the possibility of reducing or altogether eliminating the disruption and disturbance of fetal brain development in the NICU. The randomized scientific trials to date, conducted by the PI and by independent investigators at other settings after formal training show consistent significant neurobehavioral and neurophysiological improvements for the experimental groups across sites and studies.